Seasonality of Continental Extratropical-Cyclone Wind Speeds Over Northeastern North America

Abstract

This study investigates the seasonality of near-surface wind speeds associated with extratropical cyclones (ETCs) over northeastern North America using a global reanalysis data set during 1979–2020. As opposed to most studies that emphasize winter storms, ETCs during the fall exhibit significantly stronger 10-m winds over this region due to the slightly stronger continental cyclones and significantly weaker low-level stability during that time of the year. Also, ETCs favor inland lakes and Hudson Bay during the low-ice-content fall season, leading to lower surface roughness. Combining these results, we derive simple linear regressions to predict the 10-m wind speed given three variables: 850-hPa wind speed, low-level Richardson number, and surface roughness length. This formula captures the observed seasonality and serves as a valuable tool for cyclone near-surface wind risk assessment.